The machinery for connecting wires to electrical connectors is customarily used for the automatic production of harnesses in which electrical connectors having multiple contacts are sequentially supplied to the pressing section of the equipment, wherein multiple electrical wires are fed and pressed into the respective pressure-type contacts of the connectors.
In this description, the term "pressure" means the method according to which insulated electrical wires are pressed into slots made in contacts which results in insulation being cut and the core of the wire making an electrical connection with the contact, and wherein the "pressure-type" contacts are designed in such a way that it has a portion in which an insulated electrical wire is inserted by pressure, thus cutting through the insulation, and resulting in an electrical connection between the wire core and the contact.
In some of the equipment for making harnesses, for purposes of increased productivity, a number of electrical connectors are arranged in a row and simultaneously supplied to the pressure insertion section of the equipment, and the wires intended for connection to these connectors are also arranged in a row and supplied to the pressure insertion section, after which, a number of contacts become connected to their respective wires in one operation, thus making it possible to produce a number of harnesses in one operation. The simultaneous manufacture of a number of harnesses in one operation results in a substantial increase in productivity in the area of electrical harness making.
The conventional method of electrical harness production using special equipment and arranging them in a row calls for the accurate positioning of the connectors by selecting a point of reference, for example, a side surface of the side-most connector, then the side surface of the connector next to it, and so on.
The deciding factor in implementing the task of positioning the electrical wires supplied to the device making pressure connections and the "stuffer", which actually makes such connections, is the pressure-type contacts contained in the electrical connectors.
However, if the positioning is carried out by the conventional method described above, that is, by using the side surfaces of a number of electrical connectors arranged in a row, then the error over the total length of the connectors will have a cumulative effect. As a result, if the tolerance of the electrical wire pitch is .+-.0.3 mm and the tolerance of the connector housing length is .+-.0.1 mm, then the number of connectors simultaneously used in harness-making should not exceed three. Therefore, the number of electrical connectors which can be arranged in a row is limited by the consideration that the cumulative error in the external dimensions of the connector housings would not affect the quality of the pressure connection. In order to increase the number of such connectors, it is necessary to manufacture electrical connectors with a higher precision of external dimensions, but this would be a very difficult task. Additionally, this consideration was a major obstacle hampering the increase in productivity of the harnesses.